var subNavTimeout = null;
		var currentSubNav = ""; // keep reference to currently displayed subNav
	
	   /* Show subnav below nav
		 * subnav - subnav list to display
		 * nav - nav item to display under
		 */
		function showSubNav(subnav, nav)
		{
			//alert('showsubnav '+subnav);
			// close other subNav if currently displaying
			if (currentSubNav != "" && currentSubNav != subnav)
			{
				hideSubNav();
			} 
			
			// clear timeout if set 
			if (subNavTimeout != null)
			{
				clearTimeout(subNavTimeout);
				subNavTimeout = null;
			}
			
			// move into position and display
			xMoveTo(subnav, xPageX(nav), xPageY(nav) + xHeight(nav));
			xDisplay(subnav, "block");
			
			currentSubNav = subnav;
		}
		
		// hide current subNav
		function hideSubNav()
		{
			xDisplay(currentSubNav, "none");
			currentSubNav = "";
		}